I was suprise too about this, I would have expected to lose my tanks advancing them without infantry.
Why does infantry seem so weak?
Look at it this way 11 soldiers vs 3 tanks, the tanks are going to win. In the CM games, infantry is normally company size 30-40 men, plus anti-tank,and MG squads,in TOW an infantry unit is 10 men + leader. In CM the infantry leader unit is 3 or 4 men, in TOW is 1 guy with a pistol. In TOW an anti-tank unit is 1 guy with a ATR or Bazoka, in CM is two or three men. So in a typical CM battle 3 tanks vs. 1 infantry company you are going against 4X or 5X times as many men, weapons, and firepower the infantry normally win.